Coffee is a well-known drink, generally prepared as a hot water or steam extract of roast and ground coffee beans. A widespread form of coffee, is that of instant coffee. Therein the extracted coffee is turned into soluble particles (typically by spray-drying or freeze-drying). These particles can be reconstituted into liquid coffee, generally by dissolving a recommended amount of the particles in hot water.
An ongoing challenge in making soluble coffee particles, is to provide such particles that, upon dissolution in hot water, will result in a liquid coffee that resembles freshly extracted coffee as much as possible. This has been an issue for coffee producers all over the world as of the coming into existence of soluble coffee. Yet, the general consumer will be familiar with the perception, when smelling and tasting the liquid resulting from dissolving soluble coffee particles in hot water, that said liquid cannot favorably compare to freshly made coffee.
The foregoing issue has been attempted to be resolved by various improvements in the process of extracting coffee, and concentrating coffee extracts, for use in making soluble coffee particles. A particularly useful process, e.g., is that disclosed in WO 2007/043873, which results in better aromas.
A particular desire in providing an instant coffee resides in making soluble coffee particles that generate a smell that is comparable to that of freshly roasted coffee. In this respect a method has been proposed in U.S. Pat. No. 1,836,931 to impart coffee aroma to soluble coffee. In this method, soluble coffee granules are mixed with freshly roasted coffee. The soluble coffee granules and the freshly roasted coffee are maintained in intimate contact for some time, and thereafter separated. The freshly roasted coffee in U.S. Pat. No. 1,836,931 is preferably ground. The time during which the intimate contact takes place is typically 24 hours.
The method as disclosed in the foregoing reference, however, comes with a drawback in that it provides the soluble coffee particles with only a low content of aroma, and particularly of 2-methylpyrazine. Also, in respect of the aforementioned ancient disclosure of 1931, an improvement is desired in respect of the preservation of aromas upon storage of the soluble coffee.
In EP 0 144 785, a drawback of the process disclosed in U.S. Pat. No. 1,836,931 is recognized, in the sense that the roast and ground coffee is difficult to separate from the instant coffee to be aromatized (i.e., the soluble coffee particles). The teaching of EP 0 144 785 therefore concerns a process that transfers volatile aromas from roast and ground coffee by heating, whilst the roast and ground coffee is out of contact with the instant coffee. This, however, is less desired from a process point of view, as it requires energy for heating. Also, it requires installing equipment not normally present in coffee production, to allow evaporated aromas from the roast and ground coffee to be transferred to the soluble coffee particles. In EP 0 144 785 it is further taught to add an amount of oily substance to the instant coffee, in order to improve the retention of aroma. The addition of oil is not desired, as this could change the appearance of the liquid coffee obtained by reconstitution of the soluble coffee particles. Also from a regulatory perspective, it is not generally desired to add foreign substances to coffee particles.